As well known, a crusher is used to crush materials used in various industries as well as fibroid materials and sponge materials into minute grains. The crusher has been suggested in various types. By way of example, a rice hull crusher was assigned Korean Patent Application No. 34568 filed in 1996.
As shown in FIGS. 1a and 1b (FIGS. 2 and 5 of Korean Patent Application No. 34568), the rice hull crusher comprises: a crushing vessel having a crushing part 12 which is formed in a direction of an inlet 111 and a discharging part 11 which is formed in a direction of an outlet 112; a coupler 15 being directly connected to a power shaft 14 which is installed at the center of the crushing vessel 11 to be rotated at a high speed; an impeller 16 being fixed to a side of the coupler in a direction of the crushing part 12 to generate a whirlwind; a ring frame 17 being fixed to the crushing vessel 11 on an outer wall of the impeller 16 and allowing pulverized rice hull to pass through the discharging part 13; and a discharging fan 18 being fixed to a side of the coupler in a direction of the discharging part 13 to discharge the pulverized rice hull of the discharging part 13 to the outlet 112.
In the crush hull crusher, a crushing path is made in a horizontal-type and a crushing zone is made in a one step-type, such that it is applicable only to pulverization of a foxtail millet having relatively large particle size like the rice hull. It has a difficulty in pulverization of a fibroid material and a sponge material which require minute particle size.
In particular, crushed grains are progressed in one direction, such that a turbulence doesn't occur but a laminar flow occurs, thereby deteriorating collision effect of the crushed grains and resulting in non-uniform particle size. A temperature of the crusher is increased since the crushing process is repeatedly performed, whereby physical properties of the crushed object are changed due to the temperature increase.
Further, the crusher has another problem in economical effect. Since the impeller and the discharging fan are connected to one power shaft, if the crusher is operated for a long time, a severe vibration is caused due to a bending of the power shaft, whereby a cost for repairing and maintaining the crusher is greatly increased due to damage on a bearing. In addition, the crusher has still another problem. Since the discharging fan is formed on an external peripheral surface of a pipe, fine powder generated during the crushing operation is stuck to an internal peripheral surface of the pipe and the alien substance stuck to the internal peripheral surface of the pipe drops off during operation and gets to be included in a normally crushed grain, thereby deteriorating quality.
The applicant disclosed a crusher(Korean Patent Application No. 59427, filed in 1999) wherein a first crushing is performed by forming turbulence and making grains collide together, a second crushing is performed by delaying a residence time of the first crushed grain and shearing the first crushed grain at the same time, and a third crushing is performed by stirring the second crushed grain at a high speed and making the same colliding together. According to the crusher, a heat radiation area of a casing is enlarged so that heat generated inside can be effectively discharged.
As drawn in FIG. 2, the crusher has a crushed object inlet 211 at the center of an upper part of a top casing 21, an air inlet 212 on a side, a discharging mechanism 221 on a side of a lower part of a casing 22 to discharge a completely crushed grain to the outside, an impeller 23 being mounted on an upper part of a rotary shaft S at the center of the ring gear casing 22, and a discharging wing 231 on an inside corresponding to the discharging mechanism 221, the crusher comprises: a first crushing part 24 including a central rotary wing 241 and a first rotary wing 242 which are integrally formed with a first rotary plate 233 on an inside and an outside of an upper end of a fixing member 232 rested on an upper part of the impeller 23, and also including a first ring gear 243 which is formed on an inside wall of the ring gear casing 22 corresponding to the first rotary wing 242; a second crushing part 25 including radially spaced-apart second rotary wings 251 between an edge portion of a lower surface of the first rotary plate 233 and an edge portion of an upper part of a second rotary plate 234 horizontally fixed to a lower end of the fixing member 232, and including a second ring gear 252 which is formed on an inside wall of a central part of the ring gear casing 22 corresponding to a side of the second rotary wings 251; a third crushing part 26 including radially spaced-apart third rotary wings 261 which form double steps on an edge portion of a lower surface of the second rotary plate 234, and including a third ring gear 262 which is formed on an inside wall of a lower part of the ring gear casing 22 corresponding to a side of the third rotary wings 261; and a heat radiation groove 222 being formed on a surface of the ring gear casing 22.
In the earlier application crusher, the first, second, and third crushing parts are formed in a vertical gravity settling type, such that as a residence time of the crushed material becomes shorter, a crushing effect is deteriorated. The third crushing part is semicircular-shaped, such that a crushing efficiency with respect to a crushed object containing lots of fibroid material is deteriorated.
All revolving bodies are connected to one fixing member, such that a high vibration is caused. A part of a bearing for supporting the rotary shaft is positioned inside the crushing part, such that a temperature within the crushing part is increased due to a friction. Therefore, viscosity of grease injected into the bearing is deteriorated in a short time, causing a burning of the bearing. A load is applied respectively to a rotational direction and an axial direction during the operation, thereby causing a greater load.
Furthermore, the discharging wings are radially connected around the external peripheral surface of the pipe, such that the fine crushed grain is stuck to the inside of the pipe and the alien substance stuck to the internal peripheral surface of the pipe drops off during the operation and gets to be included in the normally crushed grain, thereby deteriorating quality. Moreover, in order to clean the inside of the equipment, a plurality of multi-stepped cases should be disadvantageously dismantled and all components inside should be taken to pieces.